MAELSTROM data policy: https://zenodo.org/records/15030538

MAELSTROM data access request form: https://zenodo.org/records/15030591

The data were collected in April 2023 by CNR- ISMAR VE within the MAELSTROM project with the aim to map marine litter on the seafloor. A Kongsberg EM-2040c compact single head multi-frequency multibeam system (MBES), 512 beams per swath, 1° beamwidth at 400 KHz, was used, selecting an operational frequency of 320 KHz. The Multibeam was pole-mounted on the CNR research vessel Litus, a 11-m-long boat with 1.5-m-deep draft. The acquisition system is furnished with a Seapath 380 system, supplied by Real Time Kinematic (RTK) online corrections and integrated with the Kongsberg motion sensor MRU 5 and with a Dual Antenna GPS, that allow to take in account for ship positioning and for pitch, roll, heave and yaw movements. The system was completed by a Valeport mini SVS sensor to continuously measure the sound velocity for the beamforming and by a Sound velocity profiles (SVPs).

The collected data were processed by CNR- ISMAR VE with the Caris HIPS & SIPS 11 software following the standard procedures for data conversion, tide correction (tide data provided by ISPRA, referred to the ZMPS 1897), creation of surfaces, cleaning of spurious data and application of refraction coefficients for the correction of speed of sound errors.